Hinged fork for fork-lift trucks



Nov. 11-, 1969 c. SAWYER 3,477,600

HINGED FORK FOR FORK-LIFTTRUCKS Filed Feb. 6. 1967 2 Sheets-Sheet lINVEN TOR. EDWARD C. SAWYER ATTORNEYS Nov. 11, 1969 c. SAWYER 3,477,600

HINGE!) FORK FOR FORK-LIFT TRUCKS Filed Feb. '6. 1967 2 Sheets-Sheet 2INVENTOR. EDWARD C. SAWYER ATTORNEY j 3,477,600 HINGED FORK FORFORK-LIFT TRUCKS Edward C. Sawyer, 9200 River Valley Drive, Brighton,Mich. 4811.6 Filed Feb. 6, 1967, Ser. No. 614,230

Int. 01. B661? 9/16 us. Cl. 214-700 Claims ABSTRACT OF THE DISCLOSUREThe fork-lift truck has a verticallymovable carriage and a lifting forkor forks extending outwardly from the carriage. Two pins mount the innerend of each fork on the carriage. If only one pin is' inserted, the forkcan oscillate vertically so that it can be worked up and down andgradually inserted under a load. When both pins are inserted, the forkis locked in a substantialy horizontal position for conventional liftingand transfer of the load.

BACKGROUND OF THE INVENTION The invention relates generally to liftingdevices and refers more particularly to fork-lift trucks. Heretofore,the forks were rigid. In accordance with the present invention, theforks can be made r'igidfor conventional lifting and transfer of a load,or they can be made free to oscillate vertically so that they can beworked up and down to facilitate the gradual insertion of the forksunder the load and the initial partial elevation of the load. Whileheretofore the rigidly mounted forks could be wedged with diflicultyunder some loads if not too heavy, the hinged forks of the presentinvention have a great mechanical advantage due to their fulcruming orlevering action, permitting them to be wedged under much greater loadswith the power available on the truck.

SUMMARY OF THE INVENTION It is an essential object of the invention toprovide a lifting device having a lifting fork (or forks) which can bemade rigid for conventional lifting and transfer of a load or which canbe made free to oscillate vertically to facilitate the gradual insertionof the fork (or forks) under the load with a fulcruming or leveringaction.

Another object is to provide a hinge pin and a removable locking pin forthe fork.

Another object is to provide the lifting device as a part of a fork-lifttruck.

Another object is to provide a fork which can be used as a boom fromwhich a hook may be suspended.

Another object is to provide the lifting device with a single controlfork or with two laterally spaced forks, and to taper the ends of theforks to facilitate their insertion under a load.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings, wherein:

FIGURE 1 is a perspective view of a fork-lift truck embodying myinvention.

FIGURE 2 is a sectional view taken on the line 2-2 of FIGURE 1.

FIGURE 3 is a fragmentary sectional view taken on the line 3-,3 ofFIGURE 2.

FIGURES 4 and 5 are diagrammatic views showing how the hinged action ofthe forks enables them to be gradually worked under a load.

FIGURE 6 is a fragmentary perspective view showing a modification.

FIGURE 7 is a fragmentary side view of the structure in FIGURE 6.

-United States Patent 0 3,477,600 Patented Nov. 11, 1969 "ice FIGURE 8is a sectional view taken on the line 8-8 of FIGURE 6.

Referring now more particularly to the drawings, and especially toFIGURES 1-5, the reference numeral 10 generally indicates a fork-lifttruck having a conventional body 12 and ground engaging wheels 14. Anysuitable motor and drive unit may be provided for the operation andmovement of the truck.

On the front end of the truck there is rigidly mounted a vertical frame16 which includes a pair of laterally spaced, vertical uprights 18connected at the top by a crossmember 20. There is a vertical hydrauliccylinder 22 mounted in fixed position between the uprights. A piston rod24 extends through the upper end of the cylinder, being connected to apiston 23 reciprocable within the cylinder. A head 26 is mounted uponthe upper end of the rod having a pair of freely turning sprockets 28mounted thereon in laterally spaced relation on horizontal axes. Chains30 are secured at one end to the upright frame 16 and extend over thesprockets 28. From the sprockets, the chains extend downward and aresecured at their opposite or lower ends to the carriage 32.

The carriage 32 comprises a carriage plate 34 which as shown issubstantially rectangular and is disposed in a vertical plane formovement up and down on the frame 16. As seen in FIGURE 2, the uprights18 are in the form of channels opening toward one another. On the rearsides of the carriage plate 34 there are the generally L-shaped retainerstrips 36 which engage the adjacent flanges of the channel-shapeduprights 18 to guide the vertical movement of the carriage 32 andprevent it from separating from the upright frame 16.

The carriage plate 34 has mounted thereon a pair of laterally spaced,vertical channels 40 and 42 which are spaced equal distances form and onopposite sides of the center of the plate and open in a forwarddirection. Each of the channels 40, 42 has in each flange a pair ofhorizontally spaced holes 44 and 46 at the bottom, and likewise in eachflange a pair of horizontally spaced holes 48 and 50 at the top. Theholes in the two flanges are aligned.

A pair of elongated forks 52 and 54 are mounted on the carriage 32. Theforks are identical. The rear or inner end of each fork has a pair ofhorizontally spaced holes 56 and 58. The spacing between holes 56 and 58is the same as the spacing between holes 44, 46 and holes 48, 50.

Two pins are provided for each fork. The number 60 refers to the hingepin and the number 62 refers to a removable locking pin. Actually bothpins may be removable but it is necessary only that the locking pin 62be removable.

The forks 52 and 54 are shown locked in a substantially horizontalposition in FIGURES l and 2. This is accomplished by the insertion ofboth pins 60 and 62 in the holes 44 and 46 respectively. The pins ofcourse extend through the aligned holes 56 and 58 in the fork.Obviously, the forks could be secured by the pins 60 and 62 in the holes48, 50 so as to extend substantially horizontally from the upper ends ofchannels 40 and 42.

When both the hinge pin and the locking pin are inserted to lock theforks 52 and 54 in substantially horizontal position, the forks may beoperated in a conventional manner to lift and transfer a load. Thecylinder 22 will be operated by hydraulic fluid to extend the pistonupwardly so as to elevate the carriage 32 and raise the load. It will benoted that the lower surfaces of the outer or forward ends of the forks52, 54 are tapered as indicated at 66 in order to facilitate theinsertion of the forks under the load.

When an extremely heavy load is to be lifted, it is sometimes extremelydiflicult or impossible to work the forks of a conventional truck underthe load in the narrow space provided between the floor and the bottomof the load. This is primarily because the forks on conventional trucksare rigidly mounted and therefore are not capable of being levered orfulcrumed so as to take maximum advantage of the available lifting poweron the truck.

In accordance with the present invention, the locking pins 62 areremovable so that the fork may be oscillated vertically about the hingepin 60. FIGURES 3, 4 and 5 illustrate the hinge action of the forks whenthe locking pin 62 is removed. FIGURE 4 illustrates the initial leveringaction, the load being designated by the reference character L and thefork being shown at 52. Both forks will act together for this purpose.Since the fork is tapered at its outer or forward end, it may beinserted under the adjacent edge of the load. Then, by operation ofcylinder 22 to effect an up and down movement of the carriage 32 andwith forward traction applied on the wheels of the truck, the forks maybe gradually forced under the load. FIGURE 4 shows the manner in whichthe load may be initially elevated in dotted lines. It will be notedthat the fork has a levering or fulcruming action, the fulcrum being atthe forward or outer end of the lever. Obviously, a very considerablemechanical advantage is achieved.

FIGURE 5 shows the adjacent edge of the load partially elevated andblocked up by a block 70. The fork may then be further inserted for evengreater elevation of the adjacent edge of the load by the operation ofcylinder 22 and carriage 32. For this purpose, if desired, a furthersupport 74 may be inserted for the front end of the fork.

After the fork or forks have been forced far enough under the load, theload may be lifted in the usual manner by elevation of carriage 32. Insome cases, as where the load is unusually heavy, the load may bestrapped to the truck and then dragged or pulled or pushed over theground while the forks extend under the load and at least partiallysupport it.

FIGURES 6-8 illustrate a modification of the invention in which thefork-lift truck 10 is substantially the same as the one previouslydescribed, having the body 12 and ground engaging wheels 14. The uprightframe 16 as well as the cylinder 22 and chains for lifting the carriageare also substantially the same. However, the carriage structure itselfand including the forks are different. The carriage 80 has a carriageplate 82 which is rectangular and disposed vertically and connected tothe lower ends of the chains so that it may be moved vertically withrespect to the frame 16 in the same manner as the carriage 32 previouslydescribed. As in the previous instance, L-shaped strips 84 on the backof the carriage plate 82 engage the adjacent flanges of the uprights 18to guide and prevent separation of the carriage from the upright frame.

The carriage includes a centrally located, vertically extending channel86 which opens in a forward direction. The channel 86 is of considerablelength, extending a substantial distance above the carriage plate. Eachflange of the channel is provided with pairs of holes 88 and 90, thepairs being spaced apart vertically. The holes of each pair are spacedfrom one another horizontally. The holes of one flange are respectivelyaligned with the holes of the other flange to receive the hinge pin 60and locking pin 62 so as to support the fork 92 at the desiredelevation. The fork 92 is shown with its inner end pinned to the lowestset of holes 88, 90 by the hinge pin 60 and the removable locking pin62. The fork 92 is of the same construction as the forks 52, 54previously described.

The fork-lift truck shown in FIGURES 6-8 has only the single fork 92which is centrally located With respect to the carriage. This fork isparticularly intended for use in the movement of loads by having themstrapped to the lift truck and dragged or pushed or pulled over thefloor when the fork is inserted under the load. When operated in thismanner, the crosspiece 94 will be removed from the fork. i iie'l Thefork 92, when it is desired to elevate a load clear of the ground andtransfer it while in that position, will have a crosspiece 94 assembledwith it to provide a broader support for the load. The crosspiece 94 isan elongated member having a central through-passage 96 for receivingthe fork 92. The crosspiece is thus merely slipped on the fork and maybe held thereby a locking pin if desired. In this position, thecrosspiece 94 extends at right angles to the fork and is disopsed at anypoint desired between the ends of the fork. The opening 96 in thecrosspiece is shaped to have a close fit with the fork so that by reasonof the non-circular cross-section of the fork and the opening, thecrosspiece will be held from turning or rotating on the fork.

The reason for providing a plurality of sets of the holes 88, along thelength of the channel 86 is to make it possible to mount the fork 92 atany desired position of elevation. For example, if it is desired to movea load from a 4-foot level to a 10-foot level it may be desirable tomount the fork in a set of holes spaced four feet from the bottom of thechannel.

The fork 92 can also be utilized as a boom from which a hook may besuspended on a cable. In FIGURE 7, the fork is shown at 92' in theposition it might assume as a boom. In this position, the hinge pin 60is installed as is the locking pin 62, but the locking pin instead ofextending through the hole provided in the fork 92, extends under thefork so as to support the fork in the upwardly inclined position shown.

FIGURE 7 also shows the channel in a dotted line position in which it isextended upwardly, with the fork 92 mounted in a set of holes at theupper end of the channel.

It will be understood of course that in connection with the FIGURE 1form of the invention the channels 40, 42 may be made as long as desiredand may even extend to the full height of the channel 86 if desired,depending upon the use that is to be made of the lift truck. It will bealso understood in connection with the embodiment in FIGURE 1 that thelocking pin 62 may be used to support either or both forks 52, 54 at anincline so that they may serve as a boom in the manner illustrated anddescribed in connection with FIGURES 6-8.

What I claim as my invention is:

1. A lifting device comprising a wheeled vehicle, an upright framemounted on said vehicle, a carriage movable up and down relative to saidframe, power means for moving said carriage, a lifting fork extendingoutwardly from said carriage, a hinge pin mounting the inner end of saidfork on said carriage for vertical swinging, means for selectivelylocking said fork against vertical swinging in a substantiallyhorizontal position, said locking means comprising a removable pinspaced from said hinge pin, said carriage including an upright having aplurality of vertically spaced pairs of holes, the holes of each pairbeing spaced apart and adapted to receive said hinge pin and saidremovable pin to lock said fork in substantially horizontal position.

2. The lifting device defined in claim 1, wherein said holes of eachpair are horizontally spaced, the inner end of said fork having holesspaced apart the same distance as said holes of each pair so as to berespectively alignable with the latter holes for the reception of saidpins, said fork also being adapted to rest upon said removable pin at anupward inclination to serve as a boom from which a hook may besuspended.

3. The lifting device defined in claim 1, wherein said fork is laterallycentered with respect to said carriage, and an elongated support memberremovably mounted upon and extending at right angles to said forkbetween its ends.

4. The lifting device defined in claim 1, wherein a second lifting forkextends outwardly from said carriage,

5 6 a second hinge pin mounts the inner end of said second ReferencesCited fork on said carriage for vertical swinging in laterally UNITEDSTATES PATENTS spaced relation to the first-mentioned fork, and a second2 469 1 7 5 1949 Wamock et 1 214 7 9 removable pin spaced from saidsecond hinge pin for 2,545,417 3/1951 Ulinski 214-750X selectivelylocking said second fork against vertical swing- 5 2,558,638 11/1953 ingin a substantially horizontal position, said forks being 32;

equally spaced from and located on opposite sides of the 3,358,86312/1967 Griffith et X center of said carriage.

5. The lifting device defined in claim 4, wherein the 10 GERALD FORLENZAPnmary Examiner outer ends of said forks are tapered to facilitateinser- J. SPAR, Assistant Examiner tion under a load to be lifted. L

